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Estimation of the amount of refrigerant in artificial ground freezing for subsea tunnel

해저터널 인공 동결공법에서의 냉매 사용량 산정

  • Received : 2018.01.02
  • Accepted : 2018.02.26
  • Published : 2018.03.31

Abstract

Subsea tunnel can be highly vulnerable to seawater intrusion due to unexpected high-water pressure during construction. An artificial ground freezing (AGF) will be a promising alternative to conventional reinforcement or water-tightening technology under high-water pressure conditions. In this study, the freezing energy and required time was calculated by the theoretical model of the heat flow to estimate the total amount of refrigerant required for the artificial ground freezing. A lab-scale freezing chamber was devised to investigate changes in the thermal and mechanical properties of sandy soil corresponding to the variation of the salinity and water pressure. The freezing time was measured with different conditions during the chamber freezing tests. Its validity was evaluated by comparing the results between the freezing chamber experiment and the numerical analysis. In particular, the freezing time showed no significant difference between the theoretical model and the numerical analysis. The amount of refrigerant for artificial ground freezing was estimated from the numerical analysis and the freezing efficiency obtained from the chamber test. In addition, the energy ratio for maintaining frozen status was calculated by the proposed formula. It is believed that the energy ratio for freezing will depend on the depth of rock cover in the subsea tunnels and the water temperature on the sea floor.

Acknowledgement

Grant : 고수압 초장대 해저터널 기술자립을 위한 핵심요소 기술개발

Supported by : 국토교통과학기술진흥원

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